When you call for heat and nothing happens — the furnace starts but never lights, or the burners ignite briefly and then shut off — you have an ignition failure. On Trane furnaces, this typically triggers a 2-flash fault code after the control board has attempted and failed ignition three times. This guide walks through …
A 3-flash fault code on a Trane furnace indicates a pressure switch fault — specifically, the pressure switch failed to close (or opened unexpectedly) during a heating cycle. This is one of the most common Trane furnace fault codes, and it has several possible causes ranging from a blocked vent (a 5-minute fix) to a …
A 4-flash fault code on a Trane furnace means the high limit switch has opened — the furnace detected that the heat exchanger was getting too hot and shut down the burners to prevent damage. This is one of the most important safety features on your furnace, and it is also one of the most …
The flame sensor is a small but critical component in your Trane furnace — and it is one of the most common causes of furnace problems. A dirty or failed flame sensor causes the furnace to light and then shut off within seconds, usually with a 8-flash fault code (low flame signal) on the control …
Trane gas furnaces use a diagnostic LED on the control board to communicate fault codes through a series of blinks. When something goes wrong, the LED flashes a specific pattern — a number of rapid blinks followed by a pause — that points to the cause of the problem. Understanding what these codes mean can …